Multi-speed transmission

ABSTRACT

A transmission is provided having an input member, an output member, four planetary gear sets, a plurality of coupling members and a plurality of torque transmitting devices. Each of the planetary gear sets includes first, second and third members. A first interconnecting member continuously interconnects the third member of the first planetary gear set with a stationary member, a second interconnecting member continuously interconnects the first member of the second planetary gear set with the stationary member, a third interconnecting member continuously interconnects the third member of the second planetary gear set with the first member of the third planetary gear set, and a fourth interconnecting member continuously interconnects the third member of the third planetary gear set with a third member of the fourth planetary gear set. The torque transmitting devices may include clutches.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/917,115 filed on May 10, 2007. The disclosure of the aboveapplication is incorporated herein by reference.

FIELD

The invention relates generally to a multiple speed transmission havinga plurality of planetary gear sets and a plurality of torquetransmitting devices and more particularly to a transmission havingeight or more speeds, four planetary gear sets and a plurality of torquetransmitting devices.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission uses a combination of torquetransmitting devices, planetary gear arrangements and fixedinterconnections to achieve a plurality of gear ratios. The number andphysical arrangement of the planetary gear sets, generally, are dictatedby packaging, cost and desired speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needfor an improved, cost-effective, compact multiple speed transmission.

SUMMARY

In an aspect of the present invention a transmission is provided. Thetransmission includes an input member, an output member first, second,third and fourth planetary gear sets each having first, second and thirdmembers, first, second, third, and fourth interconnecting members andfive torque-transmitting mechanisms. The first interconnecting membercontinuously interconnects the third member of the first planetary gearset with a stationary member. The second interconnecting membercontinuously interconnects the first member of the second planetary gearset with the stationary member. The third interconnecting membercontinuously interconnects the third member of the second planetary gearset with the first member of the third planetary gear set. The fourthinterconnecting member continuously interconnects the third member ofthe third planetary gear set with a third member of the fourth planetarygear set. The five torque-transmitting mechanisms are selectivelyengageable to interconnect one of the first, second, and third memberswith another of the first, second, and third members. Thetorque-transmitting mechanisms are selectively engageable incombinations of at least three to establish at least eight forward speedratios and at least one reverse speed ratio between the input member andthe output member.

In another aspect of the present invention a first of the five torquetransmitting mechanisms is selectively engageable to interconnect thesecond member of the second planetary gear set with the second member ofthe fourth planetary gear set.

In yet another aspect of the present invention a second of the fivetorque transmitting mechanisms is selectively engageable to interconnectthe second member of the third planetary gear set with the second memberof the fourth planetary gear set.

In yet another aspect of the present invention a third of the fivetorque transmitting mechanisms is selectively engageable to interconnectthe second member of the third planetary gear set with the second memberof the first planetary gear set.

In yet another aspect of the present invention a fourth of the fivetorque transmitting mechanisms is selectively engageable to interconnectthe first member of the fourth planetary gear set with the third memberof the fourth planetary gear set.

In yet another aspect of the present invention a fifth of the fivetorque transmitting mechanisms is selectively engageable to interconnectthe first member of the first planetary gear set with the first memberof the fourth planetary gear set.

In yet another aspect of the present invention the first, the second,the third, the fourth, and the fifth torque transmitting mechanisms areclutches.

In yet another aspect of the present invention the first members are sungears, the second members are carrier members, and the third members arering gears.

In yet another aspect of the present invention the input member iscontinuously interconnected with the second member of the secondplanetary gear set and the output member is continuously interconnectedwith the second member of the first planetary gear set.

In still another aspect of the present invention a transmission isprovided. The transmission includes an input member, an output member, afirst, second, third and fourth planetary gear sets each having first,second and third members, a first, second, third and fourthinterconnecting members and a first, second, third, fourth and fifthtorque-transmitting mechanisms. The input member is continuouslyinterconnected with the second member of the second planetary gear set,and the output member is continuously interconnected with the secondmember of the first planetary gear set. The first interconnecting membercontinuously interconnects the third member of the first planetary gearset with a transmission housing. The second interconnecting membercontinuously interconnects the first member of the second planetary gearset with the transmission housing. The third interconnecting membercontinuously interconnects the third member of the second planetary gearset with the first member of the third planetary gear set. The fourthinterconnecting member continuously interconnects the third member ofthe third planetary gear set with a third member of the fourth planetarygear set. The first torque-transmitting mechanism is selectivelyengageable to interconnect the second member of the second planetarygear set with the second member of the fourth planetary gear set. Thesecond torque-transmitting mechanism is selectively engageable tointerconnect the second member of the third planetary gear set with thesecond member of the fourth planetary gear set. The thirdtorque-transmitting mechanism is selectively engageable to interconnectthe second member of the first planetary gear set with the second memberof the third planetary gear set. The fourth torque-transmittingmechanism is selectively engageable to interconnect the first member ofthe fourth planetary gear set with the third member of the fourthplanetary gear set. The fifth torque-transmitting mechanism isselectively engageable to interconnect the first member of the firstplanetary gear set with the first member of the fourth planetary gearset. The torque-transmitting mechanisms are selectively engageable incombinations of at least three to establish at least eight forward speedratios and at least one reverse speed ratio between the input member andthe output member.

In still another aspect of the present invention a transmission isprovided. The transmission has an input member, an output member, afirst, second, third and fourth planetary gear sets each having a sungear, a carrier member, a ring gear, first, second, third and fourthinterconnecting members and first, second, third, fourth, and fifthtorque-transmitting mechanisms. The input member is continuouslyinterconnected with the carrier member of the second planetary gear set,and the output member is continuously interconnected with the carriermember of the first planetary gear set. The first interconnecting membercontinuously interconnects the ring gear of the first planetary gear setwith the stationary member. The second interconnecting membercontinuously interconnects the sun gear of the first planetary gear setwith the stationary member. The third interconnecting membercontinuously interconnects the ring gear of the second planetary gearset with the sun gear of the third planetary gear set. The fourthinterconnecting member continuously interconnects the ring gear of thethird planetary gear set with ring gear of the fourth planetary gearset. The first torque-transmitting mechanism is selectively engageableto interconnect the input member and the carrier member of the secondplanetary gear set with the carrier member of the fourth planetary gearset. The second torque-transmitting mechanism is selectively engageableto interconnect the carrier member of the third planetary gear set withcarrier member of the fourth planetary gear set. The thirdtorque-transmitting mechanism is selectively engageable to interconnectthe carrier member of the third planetary gear set with the carriermember of the first planetary gear set. The fourth torque-transmittingmechanism is selectively engageable to interconnect the sun gear of thefourth planetary gear set with the ring gear of the fourth planetarygear set. The fifth torque-transmitting mechanism is selectivelyengageable to interconnect the sun gear of the first planetary gear setwith sun gear of the fourth planetary gear set. The torque-transmittingmechanisms are selectively engageable in combinations of at least threeto establish at least eight forward speed ratios and at least onereverse speed ratio between the input member and the output member.

Further aspects and advantages of the present invention will becomeapparent by reference to the following description and appended drawingswherein like reference numbers refer to the same component, element orfeature.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1 is a lever diagram of an embodiment of an eight speedtransmission according to the present invention;

FIG. 2 is a diagrammatic view of an embodiment of an eight speedtransmission according to the present invention; and

FIG. 3 is a truth table presenting the state of engagement of thevarious torque transmitting clutches in each of the available forwardand reverse speeds or gear ratios of the transmission illustrated inFIGS. 1 and 2.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

At the outset, it should be appreciated that the embodiments of theeight speed automatic transmission of the present invention have anarrangement of permanent mechanical connections between the elements ofthe four planetary gear sets. For example, a first component or elementof a first planetary gear set is permanently coupled to a ground or thetransmission housing. A first component or element of a second planetarygear set is also permanently coupled to a ground or the transmissionhousing. A second component or element of the second planetary gear setis permanently coupled to a second component or element of the thirdplanetary gear set. Finally, a first component or element of the thirdplanetary gear set is permanently coupled to a first component orelement of a fourth planetary gear set.

Referring now to FIG. 1, an embodiment of an eight speed transmission 10is illustrated in a lever diagram format. A lever diagram is a schematicrepresentation of the components of a mechanical device such as anautomatic transmission. Each individual lever represents a planetarygear set wherein the three basic mechanical components of the planetarygear set are each represented by a node. Therefore, a single levercontains three nodes: one for the sun gear, one for the planet gearcarrier, and one for the ring gear. The relative length between thenodes of each lever can be used to represent the ring-to-sun ratio ofeach respective gear set. These lever ratios, in turn, are used to varythe gear ratios of the transmission in order to achieve appropriateratios and ratio progression. Mechanical couplings or interconnectionsbetween the nodes of the various planetary gear sets are illustrated bythin, horizontal lines and torque transmitting devices such as clutchesare presented as interleaved fingers. Further explanation of the format,purpose and use of lever diagrams can be found in SAE Paper 810102, “TheLever Analogy: A New Tool in Transmission Analysis” by Benford andLeising which is hereby fully incorporated by reference.

The transmission 10 includes an input shaft or member 12, a firstplanetary gear set 14 having three nodes: a first node 14A, a secondnode 14B and a third node 14C, a second planetary gear set 16 havingthree nodes: a first node 16A, a second node 16B and a third node 16C, athird planetary gear set 18 having three nodes: a first node 18A, asecond node 18B and a third node 18C, a fourth planetary gear set 20having three nodes: a first node 20A, a second node 20B and a third node20C and an output shaft or member 22.

The second node 14B of the first planetary gear set 14 is coupled to theoutput member 22. The third node 14C of the first planetary gear set 14is coupled to a ground or transmission housing 50. The first node 16A ofthe second planetary gear set 16 is also coupled to the ground ortransmission housing 50. The second node 16B of the second planetarygear set 16 is coupled to the input member 12. The third node 16C of thesecond planetary gear set 16 is coupled to the first node 18A of thethird planetary gear set 18. The third node 18C of the third planetarygear set 18 is coupled to the third node 20C of the fourth planetarygear set 20.

A first clutch 26 selectively connects the second node 16B of the secondplanetary gear set 16 and the input member 12 to the second node 20B ofthe fourth planetary gear set 20. A second clutch 28 selectivelyconnects the second node 18B of the third planetary gear set 18 to thesecond node 20B of the fourth planetary gear set 20. A third clutch 30selectively connects the second node 18B of the third planetary gear set18 to the second node 14B of the first planetary gear set 14. A fourthclutch 32 selectively connects the third node 20C of the fourthplanetary gear set 20 to the first node 20A of the fourth planetary gearset 20. A fifth clutch 34 selectively connects the first node 20A of thefourth planetary gear set 20 to the first node 14A of the firstplanetary gear set 14.

Referring now to FIG. 2, a stick diagram presents a schematic layout ofthe embodiment of the eight speed transmission 10 according to thepresent invention. In FIG. 2, the numbering from the lever diagram ofFIG. 1 is carried over. The clutches and couplings are correspondinglypresented whereas the nodes of the planetary gear sets now appear ascomponents of planetary gear sets such as sun gears, ring gears, planetgears and planet gear carriers.

For example, the planetary gear set 14 is a planetary gear set thatincludes a sun gear member 14A, a planet gear carrier member 14B and aring gear member 14C. The sun gear member 14A is connected for commonrotation to a first shaft or interconnecting member 52. The planet gearcarrier member 14B rotatably supports a set of planet gears 14D (onlyone shown) and is connected for common rotation with a second shaft orinterconnecting member 54 and output shaft 22. The planet gears 14D areconfigured to intermesh with the sun gear member 14A and the ring gearmember 14C. The ring gear member 14C is permanently connected to groundor transmission housing 50 through a third shaft or interconnectingmember 56.

The input shaft or member 12 is continuously connected to an engine (notshown) or to a turbine of a torque converter (not shown). The outputshaft or member 22 is continuously connected with the final drive unitor transfer case (not shown).

The planetary gear set 16 is a planetary gear set that includes a sungear member 16A, a planet carrier member 16B that rotatably supports aset of planet gears 16D and a ring gear member 16C. The sun gear member16A is permanently connected to ground or transmission housing 50through a fourth shaft or interconnecting member 58 in order to restrictthe sun gear member 16A from rotating relative to the ground ortransmission housing 50. The planet carrier member 16B is connected forcommon rotation with input shaft or member 12. The ring gear member 16Cis connected for common rotation with the fifth shaft or interconnectingmember 60. The planet gears 16D are configured to intermesh with boththe sun gear member 16A and the ring gear member 16C.

The planetary gear set 18 is a planetary gear set that includes a sungear member 18A, a ring gear member 18C and a planet carrier member 18Bthat rotatably supports a set of planet gears 18D. The sun gear member18A is connected for common rotation with fifth shaft or interconnectingmember 60. The ring gear member 18C is connected for common rotationwith a sixth shaft or interconnecting member 62. The planet carriermember 18B is connected for common rotation with a seventh shaft orinterconnecting member 64 and an eighth shaft or interconnecting member66. The planet gears 18D are configured to intermesh with both sun gearmember 18A and ring gear member 18C.

The planetary gear set 20 is a planetary gear set that includes a sungear member 20A, a ring gear member 20C and a planet carrier member 20Bthat rotatably supports a set of planet gears 20D. The sun gear member20A is connected for common rotation with a ninth interconnecting member68. The ring gear member 20C is connected for common rotation with atenth shaft or interconnecting member 70 and with sixth shaft orinterconnecting member 62. The planet carrier member 20B is connectedfor common rotation with an eleventh shaft or interconnecting member 72.The planet gears 20D are configured to intermesh with both the sun gearmember 20A and the ring gear member 20C.

The torque-transmitting mechanisms or clutches 26, 28, 30, 32 and 34allow for selective interconnection of the shafts or interconnectingmembers, members of the planetary gear sets and the housing. Forexample, the first clutch 26 is selectively engageable to connect theeleventh interconnecting shaft or member 72 to the input member 12. Thesecond clutch 28 is selectively engageable to connect the eighthinterconnecting member 66 to the eleventh interconnecting member 72. Thethird clutch 30 is selectively engageable to connect the secondinterconnecting shaft or member 54 to the seventh interconnecting member64. The fourth clutch 32 is selectively engageable to connect the ninthinterconnecting shaft or member 68 to the tenth interconnecting shaft ormember 70. The fifth clutch 34 is selectively engageable to connect thefirst interconnecting shaft or member 52 to the ninth interconnectingshaft or member 68.

Referring now to FIGS. 2 and 3, the operation of the embodiment of theeight speed transmission 10 will be described. It will be appreciatedthat transmission 10 is capable of transmitting torque from the inputshaft or member 12 to the output shaft or member 22 in at least eightforward speed or torque ratios and at least one reverse speed or torqueratio. Each forward and reverse speed or torque ratio is attained byengagement of one or more of the torque-transmitting mechanisms (i.e.first clutch 26, second clutch 28, third clutch 30, fourth clutch 32,and fifth clutch 34), as will be explained below. FIG. 3 is a truthtable presenting the various combinations of torque-transmittingmechanisms that are activated or engaged to achieve the various gearstates. Actual numerical gear ratios of the various gear states are alsopresented although it should be appreciated that these numerical valuesare exemplary only and that they may be adjusted over significant rangesto accommodate various applications and operational criteria of thetransmission 10. An example of the gear ratios that may be obtainedusing the embodiments of the present invention are also shown in FIG. 3.Of course, other gear ratios are achievable depending on the geardiameter, gear teeth count and gear configuration selected.

To establish reverse gear, the third clutch 30, the fourth clutch 32,and the fifth clutch 34 are engaged or activated. The third clutch 30connects the second interconnecting shaft or member 54 to the seventhinterconnecting member 64. The fourth clutch 32 connects the ninthinterconnecting shaft or member 68 to the tenth interconnecting shaft ormember 70. The fifth clutch 34 connects the first interconnecting shaftor member 52 to the ninth interconnecting shaft or member 68. Likewise,the eight forward ratios are achieved through different combinations ofclutch engagement, as shown in FIG. 3.

It will be appreciated that the foregoing explanation of operation andgear states of the eight speed transmission 10 assumes, first of all,that all the clutches not specifically referenced in a given gear stateare inactive or disengaged and, second of all, that during gear shifts,i.e., changes of gear state, between at least adjacent gear states, aclutch engaged or activated in both gear states will remain engaged oractivated.

The description of the invention is merely exemplary in nature andvariations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A transmission comprising: an input member; an output member; first,second, third and fourth planetary gear sets each having first, secondand third members; a first interconnecting member continuouslyinterconnecting the third member of the first planetary gear set with astationary member; a second interconnecting member continuouslyinterconnecting the first member of the second planetary gear set withthe stationary member; a third interconnecting member continuouslyinterconnecting the third member of the second planetary gear set withthe first member of the third planetary gear set; a fourthinterconnecting member continuously interconnecting the third member ofthe third planetary gear set with a third member of the fourth planetarygear set; and five torque-transmitting mechanisms each selectivelyengageable to interconnect at least one of the first, second, and thirdmembers of the first, second, third, and fourth planetary gear sets withat least one other of the first, second, and third members of the first,second, third, and fourth planetary gear sets; and wherein thetorque-transmitting mechanisms are selectively engageable incombinations of at least three to establish at least eight forward speedratios and at least one reverse speed ratio between the input member andthe output member.
 2. The transmission of claim 1 wherein a first of thefive torque transmitting mechanisms is selectively engageable tointerconnect the second member of the second planetary gear set with thesecond member of the fourth planetary gear set.
 3. The transmission ofclaim 2 wherein a second of the five torque transmitting mechanisms isselectively engageable to interconnect the second member of the thirdplanetary gear set with the second member of the fourth planetary gearset.
 4. The transmission of claim 3 wherein a third of the five torquetransmitting mechanisms is selectively engageable to interconnect thesecond member of the third planetary gear set with the second member ofthe first planetary gear set.
 5. The transmission of claim 4 wherein afourth of the five torque transmitting mechanisms is selectivelyengageable to interconnect the first member of the fourth planetary gearset with the third member of the third planetary gear set.
 6. Thetransmission of claim 5 wherein a fifth of the five torque transmittingmechanisms is selectively engageable to interconnect the first member ofthe first planetary gear set with the first member of the fourthplanetary gear set.
 7. The transmission of claim 1 wherein the first,the second, the third, the fourth, and the fifth torque transmittingmechanisms are clutches.
 8. The transmission of claim 1 wherein thefirst members of the first, second, third, and fourth planetary gearsets are sun gears, the second members of the first, second, third, andfourth planetary gear sets are carrier members, and the third members ofthe first, second, third, and fourth planetary gear sets are ring gears.9. The transmission of claim 5 wherein the input member is continuouslyinterconnected with the second member of the second planetary gear setand the output member is continuously interconnected with the secondmember of the first planetary gear set.
 10. A transmission comprising:an input member; an output member; first, second, third and fourthplanetary gear sets each having first, second and third members, whereinthe input member is continuously interconnected with the second memberof the second planetary gear set, and the output member is continuouslyinterconnected with the second member of the first planetary gear set; afirst interconnecting member continuously interconnecting the thirdmember of the first planetary gear set with a transmission housing; asecond interconnecting member continuously interconnecting the firstmember of the second planetary gear set with the transmission housing; athird interconnecting member continuously interconnecting the thirdmember of the second planetary gear set with the first member of thethird planetary gear set; a fourth interconnecting member continuouslyinterconnecting the third member of the third planetary gear set with athird member of the fourth planetary gear set; a firsttorque-transmitting mechanism selectively engageable to interconnect thesecond member of the second planetary gear set with the second member ofthe fourth planetary gear set; a second torque-transmitting mechanismselectively engageable to interconnect the second member of the thirdplanetary gear set with the second member of the fourth planetary gearset; a third torque-transmitting mechanism selectively engageable tointerconnect the second member of the first planetary gear set with thesecond member of the third planetary gear set; a fourthtorque-transmitting mechanism selectively engageable to interconnect thefirst member of the fourth planetary gear set with the third member ofthe third planetary gear set; a fifth torque-transmitting mechanismselectively engageable to interconnect the first member of the firstplanetary gear set with the first member of the fourth planetary gearset; and wherein the torque-transmitting mechanisms are selectivelyengageable in combinations of at least three to establish at least eightforward speed ratios and at least one reverse speed ratio between theinput member and the output member.
 11. The transmission of claim 10wherein the first, the second, the third, the fourth, and fifth torquetransmitting mechanisms are clutches.
 12. The transmission of claim 10wherein the first members of the first, second, third, and fourthplanetary gear sets are sun gears, the second members of the first,second, third, and fourth planetary gear sets are carrier members, andthe third members of the first, second, third, and fourth planetary gearsets are ring gears.
 13. A transmission comprising: an input member; anoutput member; first, second, third and fourth planetary gear sets eachhaving a sun gear, a carrier member, and a ring gear, wherein the inputmember is continuously interconnected with the carrier member of thesecond planetary gear set, and the output member is continuouslyinterconnected with the carrier member of the first planetary gear set;a first interconnecting member continuously interconnecting the ringgear of the first planetary gear set with the stationary member; asecond interconnecting member continuously interconnecting the sun gearof the second planetary gear set with the stationary member; a thirdinterconnecting member continuously interconnecting the ring gear of thesecond planetary gear set with the sun gear of the third planetary gearset; a fourth interconnecting member continuously interconnecting thering gear of the third planetary gear set with ring gear of the fourthplanetary gear set; a first torque-transmitting mechanism selectivelyengageable to interconnect the input member and the carrier member ofthe second planetary gear set with the carrier member of the fourthplanetary gear set; a second torque-transmitting mechanism selectivelyengageable to interconnect the carrier member of the third planetarygear set with carrier member of the fourth planetary gear set; a thirdtorque-transmitting mechanism selectively engageable to interconnect thecarrier member of the third planetary gear set with the carrier memberof the first planetary gear set; a fourth torque-transmitting mechanismselectively engageable to interconnect the sun gear of the fourthplanetary gear set with the ring gear of the third planetary gear set; afifth torque-transmitting mechanism selectively engageable tointerconnect the sun gear of the first planetary gear set with sun gearof the fourth planetary gear set; and wherein the torque-transmittingmechanisms are selectively engageable in combinations of at least threeto establish at least eight forward speed ratios and at least onereverse speed ratio between the input member and the output member.